java - 为什么WAV文件中的字节数组看起来不像音频波形

Question

下面的代码记录，播放和“解码” wav文件。当我从文件中绘制字节数组时，它看起来像这样:



录音是我说的“测试”，它应该像这样:



有谁知道为什么wav文件中字节数组的图看起来不像真实的音频数据？

这是整个 Activity 的代码:

package com.example.wesle.noisemachine;

import android.content.Intent;
import android.media.AudioFormat;
import android.media.AudioManager;
import android.media.AudioRecord;
import android.net.Uri;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.media.MediaPlayer;
import android.media.MediaRecorder;
import android.os.Environment;
import android.widget.Toast;

import com.jjoe64.graphview.GraphView;
import com.jjoe64.graphview.series.DataPoint;
import com.jjoe64.graphview.series.LineGraphSeries;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.*;

public class ReceiveScreen extends AppCompatActivity {

    private Button buttonStart, buttonStop, buttonDecode, buttonPlay;
    private String filePath;

    private static final int RECORDER_BPP = 16;
    private static final String AUDIO_RECORDER_FILE_EXT_WAV = ".wav";
    private static final String AUDIO_RECORDER_FOLDER = "AudioRecorder";
    private static final String AUDIO_RECORDER_TEMP_FILE = "record_temp.raw";
    private static final int RECORDER_SAMPLERATE = 44100;
    private static final int RECORDER_CHANNELS = AudioFormat.CHANNEL_IN_STEREO;
    private static final int RECORDER_AUDIO_ENCODING = AudioFormat.ENCODING_PCM_16BIT;
    short[] audioData;

    private AudioRecord recorder = null;
    private int bufferSize = 0;
    private Thread recordingThread = null;
    private boolean isRecording = false;
    Complex[] fftTempArray;
    Complex[] fftArray;
    int[] bufferData;
    int bytesRecorded;
    LineGraphSeries<DataPoint> series;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_receive_screen);

        filePath = getFilename();
        final File wavfile = new File(filePath);

        buttonStart = (Button) findViewById(R.id.buttonStart);
        buttonStop = (Button) findViewById(R.id.buttonStop);
        buttonPlay = (Button) findViewById(R.id.buttonPlay);
        buttonDecode = (Button) findViewById(R.id.buttonDecode);
        buttonStop.setEnabled(false);
        buttonDecode.setEnabled(false);
        buttonPlay.setEnabled(false);

        bufferSize = AudioRecord.getMinBufferSize
                (RECORDER_SAMPLERATE,RECORDER_CHANNELS,RECORDER_AUDIO_ENCODING)*3;
        audioData = new short [bufferSize];

        buttonStart.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                buttonStart.setEnabled(false);
                buttonDecode.setEnabled(false);
                buttonPlay.setEnabled(false);
                recorder = new AudioRecord(MediaRecorder.AudioSource.MIC,
                        RECORDER_SAMPLERATE,
                        RECORDER_CHANNELS,
                        RECORDER_AUDIO_ENCODING,
                        bufferSize);
                int i = recorder.getState();
                if (i==1)
                    recorder.startRecording();

                isRecording = true;

                recordingThread = new Thread(new Runnable() {
                    @Override
                    public void run() {
                        writeAudioDataToFile();
                    }
                }, "AudioRecorder Thread");

                recordingThread.start();

                buttonStop.setEnabled(true);

                Toast.makeText(getApplicationContext(), "Recording started", Toast.LENGTH_LONG).show();

            }
        });

        buttonStop.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                buttonStop.setEnabled(false);
                if (null != recorder){
                    isRecording = false;

                    int i = recorder.getState();
                    if (i==1)
                        recorder.stop();
                    recorder.release();

                    recorder = null;
                    recordingThread = null;
                }
                copyWaveFile(getTempFilename(),filePath);
                deleteTempFile();

                Toast.makeText(getApplicationContext(), "Recording Completed", Toast.LENGTH_LONG).show();
                buttonStart.setEnabled(true);
                buttonPlay.setEnabled(true);
                buttonDecode.setEnabled(true);
            }
        });

        buttonPlay.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                buttonStart.setEnabled(false);
                buttonDecode.setEnabled(false);
                buttonPlay.setEnabled(false);
                Toast.makeText(getApplicationContext(), "Recording Playing", Toast.LENGTH_LONG).show();

                Uri myUri1 = Uri.fromFile(wavfile);
                final MediaPlayer mPlayer = new MediaPlayer();
                mPlayer.setAudioStreamType(AudioManager.STREAM_MUSIC);

                try {
                    mPlayer.setDataSource(getApplicationContext(), myUri1);
                } catch (IllegalArgumentException e) {
                    Toast.makeText(getApplicationContext(), "You might not set the URI correctly!", Toast.LENGTH_LONG).show();
                } catch (SecurityException e) {
                    Toast.makeText(getApplicationContext(), "You might not set the URI correctly!", Toast.LENGTH_LONG).show();
                } catch (IllegalStateException e) {
                    Toast.makeText(getApplicationContext(), "You might not set the URI correctly!", Toast.LENGTH_LONG).show();
                } catch (IOException e) {
                    e.printStackTrace();
                }

                try {
                    mPlayer.prepare();
                } catch (IllegalStateException e) {
                    Toast.makeText(getApplicationContext(), "You might not set the URI correctly!", Toast.LENGTH_LONG).show();
                } catch (IOException e) {
                    Toast.makeText(getApplicationContext(), "You might not set the URI correctly!", Toast.LENGTH_LONG).show();
                }

                mPlayer.start();

                buttonStart.setEnabled(true);
                buttonDecode.setEnabled(true);
                buttonPlay.setEnabled(true);
            }
        });

        buttonDecode.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                buttonStart.setEnabled(false);
                buttonDecode.setEnabled(false);
                buttonPlay.setEnabled(false);

                GraphView thegraph = (GraphView) findViewById(R.id.thegraph);
                series = new LineGraphSeries<DataPoint>();
                double x,y;
                x = 0;

                try {
                    ByteArrayOutputStream outt = new ByteArrayOutputStream();
                    BufferedInputStream in = new BufferedInputStream(new FileInputStream(wavfile));

                    int read;
                    byte[] buff = new byte[1024];
                    while ((read = in.read(buff)) > 0)
                    {
                        outt.write(buff, 0, read);
                    }
                    outt.flush();
                    byte[] audioBytes = outt.toByteArray();

                    //int[][] graphData = getUnscaledAmplitude(audioBytes, 1);

                    for(int i = 0; i < audioBytes.length;i++){


                        //System.out.println(audioBytes[i]);
                        byte curByte = audioBytes[i];
                        //int curByte = graphData[0][i];
                        y = (curByte);
                        series.appendData(new DataPoint(x,y), true, audioBytes.length);
                        x = x + 1;
                        //x = x + (1 / RECORDER_SAMPLERATE);
                    }
                    thegraph.addSeries(series);

                } catch (IOException e) {
                    e.printStackTrace();
                }

                buttonStart.setEnabled(true);
                buttonDecode.setEnabled(true);
                buttonPlay.setEnabled(true);

            }
        });

        //Code for the back button
        Button backbuttonR = (Button) findViewById(R.id.backbuttonR);
        backbuttonR.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                startActivity(new Intent(ReceiveScreen.this, MainActivity.class));
            }
        });

    }

    private String getFilename(){
        String filepath = Environment.getExternalStorageDirectory().getPath();
        File file = new File(filepath,AUDIO_RECORDER_FOLDER);
        System.out.println(file.getAbsolutePath() + "/" + System.currentTimeMillis() + AUDIO_RECORDER_FILE_EXT_WAV);
        if (!file.exists()) {
            file.mkdirs();
        }

        return (file.getAbsolutePath() + "/" + System.currentTimeMillis() + AUDIO_RECORDER_FILE_EXT_WAV);
    }

    private String getTempFilename() {
        String filepath = Environment.getExternalStorageDirectory().getPath();
        File file = new File(filepath,AUDIO_RECORDER_FOLDER);

        if (!file.exists()) {
            file.mkdirs();
        }

        File tempFile = new File(filepath,AUDIO_RECORDER_TEMP_FILE);

        if (tempFile.exists())
            tempFile.delete();

        return (file.getAbsolutePath() + "/" + AUDIO_RECORDER_TEMP_FILE);
    }

    private void writeAudioDataToFile() {
        byte data[] = new byte[bufferSize];
        String filename = getTempFilename();
        FileOutputStream os = null;

        try {
            os = new FileOutputStream(filename);
        } catch (FileNotFoundException e) {
            //TODO Auto-generated catch block
            e.printStackTrace();
        }

        int read = 0;
        if (null != os) {
            while(isRecording) {
                read = recorder.read(data, 0, bufferSize);
                if (read > 0){
                }

                if (AudioRecord.ERROR_INVALID_OPERATION != read) {
                    try {
                        os.write(data);
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }

            try {
                os.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    private void deleteTempFile() {
        File file = new File(getTempFilename());
        file.delete();
    }

    private void copyWaveFile(String inFilename,String outFilename){
        FileInputStream in = null;
        FileOutputStream out = null;
        long totalAudioLen = 0;
        long totalDataLen = totalAudioLen + 36;
        long longSampleRate = RECORDER_SAMPLERATE;
        int channels = 2;
        long byteRate = RECORDER_BPP * RECORDER_SAMPLERATE * channels/8;

        byte[] data = new byte[bufferSize];

        try {
            in = new FileInputStream(inFilename);
            out = new FileOutputStream(outFilename);
            totalAudioLen = in.getChannel().size();
            totalDataLen = totalAudioLen + 36;

            System.out.println("File size: " + totalDataLen);

            WriteWaveFileHeader(out, totalAudioLen, totalDataLen,
                    longSampleRate, channels, byteRate);

            while(in.read(data) != -1) {
                out.write(data);
            }

            in.close();
            out.close();
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

    private void WriteWaveFileHeader(
            FileOutputStream out, long totalAudioLen,
            long totalDataLen, long longSampleRate, int channels,
            long byteRate) throws IOException
    {
        byte[] header = new byte[44];

        header[0] = 'R';  // RIFF/WAVE header
        header[1] = 'I';
        header[2] = 'F';
        header[3] = 'F';
        header[4] = (byte) (totalDataLen & 0xff);
        header[5] = (byte) ((totalDataLen >> 8) & 0xff);
        header[6] = (byte) ((totalDataLen >> 16) & 0xff);
        header[7] = (byte) ((totalDataLen >> 24) & 0xff);
        header[8] = 'W';
        header[9] = 'A';
        header[10] = 'V';
        header[11] = 'E';
        header[12] = 'f';  // 'fmt ' chunk
        header[13] = 'm';
        header[14] = 't';
        header[15] = ' ';
        header[16] = 16;  // 4 bytes: size of 'fmt ' chunk
        header[17] = 0;
        header[18] = 0;
        header[19] = 0;
        header[20] = 1;  // format = 1
        header[21] = 0;
        header[22] = (byte) channels;
        header[23] = 0;
        header[24] = (byte) (longSampleRate & 0xff);
        header[25] = (byte) ((longSampleRate >> 8) & 0xff);
        header[26] = (byte) ((longSampleRate >> 16) & 0xff);
        header[27] = (byte) ((longSampleRate >> 24) & 0xff);
        header[28] = (byte) (byteRate & 0xff);
        header[29] = (byte) ((byteRate >> 8) & 0xff);
        header[30] = (byte) ((byteRate >> 16) & 0xff);
        header[31] = (byte) ((byteRate >> 24) & 0xff);
        header[32] = (byte) (2 * 16 / 8);  // block align
        header[33] = 0;
        header[34] = RECORDER_BPP;  // bits per sample
        header[35] = 0;
        header[36] = 'd';
        header[37] = 'a';
        header[38] = 't';
        header[39] = 'a';
        header[40] = (byte) (totalAudioLen & 0xff);
        header[41] = (byte) ((totalAudioLen >> 8) & 0xff);
        header[42] = (byte) ((totalAudioLen >> 16) & 0xff);
        header[43] = (byte) ((totalAudioLen >> 24) & 0xff);

        out.write(header, 0, 44);
    }

    public static final class Complex {
        // The number stored is x+I*y.
        final private double x, y;
        // I don't want to allow anyone to access these numbers so I've labeled
        // them private.

        /** Construct a point from real and imaginary parts. */
        public Complex(double real_part, double imaginary_part) {
            x=real_part;
            y=imaginary_part;
        }

        /** Construct a real number. */
        public Complex(double real_part) {
            x=real_part;
            y=0;
        }

        // A static constructor.

        /** Construct a complex number from the given polar coordinates. */
        public static Complex fromPolar(double r, double theta) {
            return new Complex(r*Math.cos(theta), r*Math.sin(theta));
        }

        // Basic operations on Complex numbers.

        /** Return the real part. */
        public double re(){
            return x;
        }

        /** Return the imaginary part. */
        public double im(){
            return y;
        }

        /** Return the complex conjugate */
        public Complex conj() {
            return new Complex(x,-y);
        }

        /** Return the square of the absolute value. */
        public double absSquared() {
            return x*x+y*y;
        }

        /** Return the absolute value. */
        public double abs() {
            // The java.lang.Math package contains many useful mathematical functions,
            // including the square root function.
            return Math.sqrt(absSquared());
        }

        // ARITHMETIC

        /** Add a complex number to this one.
         *
         * @param z The complex number to be added.
         * @return A new complex number which is the sum.
         */
        public Complex add(Complex z) {
            return new Complex(x+z.x, y+z.y);
        }

        /** Subtract a complex number from this one.
         *
         * @param z The complex number to be subtracted.
         * @return A new complex number which is the sum.
         */
        public Complex minus(Complex z) {
            return new Complex(x-z.x, y-z.y);
        }

        /** Negate this complex number.
         *
         * @return The negation.
         */
        public Complex neg() {
            return new Complex(-x, -y);
        }

        /** Compute the product of two complex numbers
         *
         * @param z The complex number to be multiplied.
         * @return A new complex number which is the product.
         */
        public Complex mult(Complex z) {
            return new Complex(x*z.x-y*z.y, x*z.y+z.x*y);
        }

        /** Divide this complex number by a real number.
         *
         * @param q The number to divide by.
         * @return A new complex number representing the quotient.
         */
        public Complex div(double q) {
            return new Complex(x/q,y/q);
        }

        /** Return the multiplicative inverse. */
        public Complex inv() {
            // find the square of the absolute value of this complex number.
            double abs_squared=absSquared();
            return new Complex(x/abs_squared, -y/abs_squared);
        }

        /** Compute the quotient of two complex numbers.
         *
         * @param z The complex number to divide this one by.
         * @return A new complex number which is the quotient.
         */
        public Complex div(Complex z) {
            return mult(z.inv());
        }

        /** Return the complex exponential of this complex number. */
        public Complex exp() {
            return new Complex(Math.exp(x)*Math.cos(y),Math.exp(x)*Math.sin(y));
        }


        // FUNCTIONS WHICH KEEP JAVA HAPPY:

        /** Returns this point as a string.
         * The main purpose of this function is for printing the string out,
         * so we return a string in a (fairly) human readable format.
         */
        // The _optional_ override directive "@Override" below just says we are
        // overriding a function defined in a parent class. In this case, the
        // parent is java.lang.Object. All classes in Java have the Object class
        // as a superclass.
        @Override
        public String toString() {
            // Comments:
            // 1) "" represents the empty string.
            // 2) If you add something to a string, it converts the thing you
            // are adding to a string, and then concatentates it with the string.

            // We do some voodoo to make sure the number is displayed reasonably.
            if (y==0) {
                return ""+x;
            }
            if (y>0) {
                return ""+x+"+"+y+"*I";
            }
            // otherwise y<0.
            return ""+x+"-"+(-y)+"*I";
        }

        /** Return true if the object is a complex number which is equal to this complex number. */
        @Override
        public boolean equals(Object obj) {
            // Return false if the object is null
            if (obj == null) {
                return false;
            }
            // Return false if the object is not a Complex number
            if (!(obj instanceof Complex)) {
                return false;
            }

            // Now the object must be a Complex number, so we can convert it to a
            // Complex number.
            Complex other = (Complex) obj;

            // If the x-coordinates are not equal, then return false.
            if (x != other.x) {
                return false;
            }
            // If the y-coordinates are not equal, then return false.
            if (y != other.y) {
                return false;
            }
            // Both parts are equal, so return true.
            return true;
        }
        @Override
        public int hashCode() {
            int hash = 3;
            hash = 83 * hash + (int) (Double.doubleToLongBits(this.x) ^ (Double.doubleToLongBits(this.x) >>> 32));
            hash = 83 * hash + (int) (Double.doubleToLongBits(this.y) ^ (Double.doubleToLongBits(this.y) >>> 32));
            return hash;
        }
    }

    public int[][] getUnscaledAmplitude(byte[] eightBitByteArray, int nbChannels)
    {
        int[][] toReturn = new int[nbChannels][eightBitByteArray.length / (2 * nbChannels)];
        int index = 0;

        for (int audioByte = 0; audioByte < eightBitByteArray.length;)
        {
            for (int channel = 0; channel < nbChannels; channel++)
            {
                // Do the byte to sample conversion.
                int low = (int) eightBitByteArray[audioByte];
                audioByte++;
                int high = (int) eightBitByteArray[audioByte];
                audioByte++;
                int sample = (high << 8) + (low & 0x00ff);

                toReturn[channel][index] = sample;

                if (audioByte == 0) {
                    System.out.println("CHANNEL COUNT");
                }
            }
            index++;
        }

        return toReturn;
    }



}

Answer 1

如果这是16位音频，则每隔一个字节将是最低有效的数据。绘制这些字节会使它看起来非常嘈杂(如您上面所述)。

像这样想，在电话簿中，姓氏由LastName，FirstName排序。这类似于为16位音频对两个字节进行排序的方式。假设名称为:

安德斯(Zoey)

安德森(Sally

)

安德鲁斯，克雷格

如果仅“绘制”姓氏，那么他们将从Anders到Anderson到Andrews的过渡非常顺利。但是，如果您在情节中还包括名字，它将从“Anders”跳到“Zoey”，然后又跳回到“Anderson”，再跳到“Sally”，依此类推。